Ionic electro-acoustic transducer



NOV. 4, 1969 s Ll ET AL 3,476,887

IONIC ELECTRO-ACOUSTIC TRANSDUCER Filed April 26; l966 INVENTORS A. L. SELIGSON R..S. LANIER ATTORNEY United States Patent 3,476,887 IUNIC ELECTRO-ACOUSTIC TRANSDUCER Arnold L. Seligson, 13317 227th St., Laurelton, N.Y. 11413, and Robert S. Lanier, 240 W. 98th St., New York, NY. 10025 Filed Apr. 26, 1966, Ser. No. 545,346 Int. Cl. H04r 23/00 US. Cl. 179-113 6 Claims ABSTRACT OF THE DISCLOSURE An ionic electro-acoustic transducer having a set of emitter electrodes spaced from a set of collector electrodes between which sets of electrodes a flow of electrons is produced by applying a voltage differential between the two sets of electrodes. Modulating means are arranged to control the flow of ions between the two sets of electrodes.

This invention relates to electro-acoustic transducers, more particularly to an improved ionic transducer employing a novel modulation technique serving to minimize production and maintenance costs and improving the efficiency of the transducer to implement its use as a loud speaker for devices such as radio receivers, phonographs, television, public address systems, or the like.

Electrical transducers, which employ ionization of a fluid medium to create sound, have been evol-ved employing a variety of ways of controlling ion flow to produce sound. One such system confines a gas, such as air, to an enclosure in which the air is heated by ionization of its molecules. The air is expanded and contracted by changing the potential of one ion-producing electrode with respect to another. If these expansions and contractions of the air are regulated to coincide with audio frequencies, and the transducer is properly coupled to an appropriately shaped horn, audible sound may result. The effectiveness of such a system is determined by the ability of the electrical power supplied to vary the heat of the gas and ambient thermal conditions and thermal inertia militates against desired audio signal production.

Another proposed technique uses cathode and anode plates proximately placed to one another. Air is forced between the anode and cathode plates and the air is ionized by placing a high voltage between the anode and cathode. The rate of passage of air therebetwee'n directly reflects these degree of ionization employed. If the potential between the plates is varied at audio frequencies audible sound results. This method requires the use of fans or other means for inducing air flow. Further, the efficiency of this system is limited by the ability of the device to transfer electrical power to the controlled flow of air between narrow openings.

Still another technique employs the creation of a cloud of negatively charged ions by the heating of a filament. The cloud of ions is moved by a fan or other means and subjected to an electrical field transverse to its direction of propagation. The efficiency of this system is limited by its ability to alter the shape or change the direction of the ion cloud. 1

In each of these prior techniques, much efliciency is lost by indirectly employing the energy used to create ions to then perform some other function. A further disadvantage is that expensive and complicated equipment must be employed.

It is accordingly an object of this invention to improve the efliciency of an ionic transducer.

It is a further object of this invention to provide an improved loud speaker having no moving parts, thus minimizing production and maintenance costs.

3,476,887 Patented Nov. 4, 1969 Another object of the invention is to, provide an ionic transducer in which desired electro-acoustic transduction can be obtained from relatively low level electrical power sources.

A further object of the invention is to provide an ionic transducer in which the power required for modulation is relatively low.

Another object of the invention is to provide an ionic transducer in which either digital or analog modulation may be employed.

It is also an object of the invention to provide an ionic transducer which is an area producer, that is in which every part of the speaker area produces sound.

Another object of the invention is to provide an ionic transducer adapted for push-pull operation.

It is with the above problems and considerations in mind that the ionic transducer of this invention has been evolved.

Briefly, the improved transducer comprises a set of emitter electrodes electrically joined together. These emitter electrodes are separated from a second set of collector electrodes. A flow of ions is produced by impressing a voltage between the two sets of electrodes. Modulating means are provided proximate to the emitter electrodes for controlling the flow of ions between the two sets of electrodes to produce audible sound.

According to a hereafter described illustrated embodiment of the invention, a series of pin-shaped electrodes are placed opposite to and parallel with a series of bar shaped electrodes. The former may be referred to as emitters and latter collectors. About each emitter is placed a cylindrically shaped electrode or modulator. A flow of ions is established between the emitters and the collectors by the application thereto of a high DC voltage. The flow of ions is controlled by impressing a varying voltage between the modulators and the emitters. Thus, if the modulators are positive with respect to the emitters, ions will be encouraged to separate from the emitters and travel to the high-potential collectors. If, on the other hand, the modulators are negative with respect to the emitters, there will be little or no ion travel to the collectors. The resulting modulation of the ion field, if performed at audio frequencies, will result in audible sound.

A feature of the invention resides in the variation of density of an electric field at the emitter electrode thus not depending on raising air to a plasma state.

Another feature of the invention resides in the fact that modulation and emission take place at the same points in space so that only electric lines of force are moved to effect modulation without requiring work in moving the ions.

The novel features of the present invention, both as to its organization and method of operation, as well as additional objects and advantages thereof, will be more fully understood from the following description, and will be described in clear, concise and exact terms in conjunction with the accompanying drawing, in which:

FIG. 1 is a perspective view of the improved transducer constructed in accordance with the invention;

FIG. 2 is a cross-sectional view on line 22 of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the improved transducer constructed in accordance with the invention taken along the line 3-3 of FIG. 2; and

FIG. 4 is a schematic cross-sectional view of a transducer made in accordance with the teachings of this invention provided with a push-pull circuit arrangement.

Referring now particularly to FIG. 1 of the drawing, there is shown an improved electrical transducer 6. A first set of electrodes, or emitters 8, are spaced from a second set of electrodes, or collectors 10. The collectors 10 are parallel to the emitters 8. Proximate to the emitters 8 and spaced therefrom is a third set of electrodes, or modulators 12.

The emitters are of a shape subject to a steep voltage gradient when placed in an electric field. Electrodes shaped as sharp pointed pins, thin wires, sharp edged strips or the like may be employed. Illustratively, the emitters 8 are shown as pointed pins, and these emitters 8 are arranged with their points in a common plane which is shown as planar, but may also be curved if desired.

The collectors 10 can have any form that permits their arrangement in an equipotential, or substantially equipotential collector plane with air passages therethrough. Satisfactory collectors may be formed by a mesh or screen, a series of spaced rods, a perforate plate, a plurality of rings or the like. Illustratively, the collectors 10 are shown as comprising a series of spaced parallel bars. The plane of the collectors 10 is arranged to lie parallel to the plane of the emitter so that all lines normal to both emitter and collector planes will be of equal length.

The modulators 12 are contoured to permit their arrangement in modulating relationship to the emitters 8. As illustrated a tube concentric with the point of the emitter 8 is satisfactory. Other suitable arrangements comprise a plate with holes, with the plate arranged in the plane of the emitter electrode points, where pointed pins or rods are employed for the emitters.

The collectors 10 are electrically connected to a first source of DC voltage IE at its positive terminal. The modulators 12 are electrically connected to a positive terminal of a second source of DC voltage E The negative terminal of the second source of DC voltage E is connected to one terminal of a two terminal source of AC voltage S, which could be for example the audio output stage of a radio or similar device (not shown). The second terminal of the source of alternating voltage S and the negative terminal of the first source of DC voltage E and the emitters 8 are connected to a common point which may be referred to as ground.

The emitters 8 are illustratively shown as arranged in a grid comprising rigid, rectangularly shaped strips of an electrical conductor 14 formed of a metal such as copper or brass. These strips 14 are arranged in a common plane parallel to, and spaced at regular intervals from, one another. Perpendicularly placed electrically conductive cross bars 16, formed of a conductive metal such as copper, are secured to the ends of the strips 14 by bolts 18 or other fastening means.

A more complete understanding of the construction of the emitters 8 and the modulators 12 can be obtained by reference to FIGS. 2 and 3. Aflixed at regular intervals to each strip 14 are pin-like projections 20 extending perpendicularly outward from the plane formed by the cross bars 16 and strips 14. The pins 20 can be attached by inserting them through holes prepunched in the strips 14 and thereafter welded in place. The pins 20 can be of steel or other electrically conductive substance suitable for the production of negatively charged ions.

The modulators 12 of the illustrated embodiment are formed by placing about the pins 20 hollow cylindrically shaped insulators 22, which can be Teflon, rubber or similar non-conducting material. The insulators 22 are shaped to fit tightly about the pins 20 in a force fit. Placed about the insulators 22 are hollow cylindrically shaped electrodes 24. The cylindrically shaped electrodes 24 which are formed of any suitable conductive material such as copper are dimensioned to fit tightly about the insulators 22. A conducting wire 26 is extended between and preferably soldered to each of the electrodes 24. The cylindrically shaped electrodes 24 are spaced from the strips 14 permitting the pins 20 to extend through and beyond the edges of the electrodes 24, as best seen in FIG. 3.

The collectors 10 as shown in FIG. 2 comprise cylindrically shaped strips or rods 28 of an electrically conductive material such as copper, arranged at spaced intervals in a common plane parallel to one another. Like the emitters 8 the rods 28 of the collectors 10 are secured at both ends to cross bars 30 by bolts 32 or other fastening means. Both the cross bars 30 and the rods 28 are formed of a conductive metal such as copper or brass.

As shown in FIG. 1 the emitters 8 are placed opposite and spaced from the collectors 10. Each strip 14 of the emitters 8 is parallel to each rod 28 of the collectors 10. The emitters 8 and collectors 10 of the transducer 6 are maintained in a desired spaced orientation to permit the circulation of air therethrough, by supports constructed of wood, plastic or other rigid insulating material.

In the FIG. 4 embodiment of the invention, a pushpull arrangement is shown in which two emitters 48 and 49 are shown arranged on opposite sides of a collector 50. Emitters 48 and 49 are constructed as above-described emitters 8 of the FIG. 1-3 embodiment, and collector 50 is constructed like collector 10.

An accelerating voltage E is impressed between each emitter 48 and 49 and the collector 50, as shown in FIG. 4. Bias voltages for emitters 48 and 49 are provided by DC voltage sources E and E respectively, and the signal is fed to the transducer through the illustrated center tapped transformer 51.

OPERATION In operation of the FIGS. l3 embodiment, the first source of DC voltage E of a high potential is placed across the collectors 10 and the emitters 8 causing negatively charged ions to flow from the emitter pins 20 to the collectors 10. The amount of ion flow from the pins 20 to the collector rods 28 is directly related to the number of pins 20, the distance between the collector rods 28 and emitter strips 14 and voltage supplied by the first DC source E This ion flow can be controlled by varying the potential (i.e. the voltage supplied by the AC source S) between the modulators 12 and emitters 8.

By way of example, ion flow sufiicient to produce sounds can be established, by inserting pins 20 in the strips 14 at a spacing of one-half inch. Strips 14 of about thickness are attached to the cross bars 16 on /1, centers. The rods 28 of the collectors 10 having a diameter of are mounted on the cross bars 30 apart. The dimensioning of the illustrative electrode array is approximately 1 /2 by 2 /2. The first source of DC voltage E has a potential of fifteen thousand volts.

The signal voltage required for modulation as placed across the modulators 12 and the emitters 8, and as supplies by the AC source S is, for example, from three hundred to four hundred volts (RMS) and the bias voltage supplied by the second source of DC voltage E is approximately 400 volts. As the voltage applied to the modulators 12 is increased to approximately 800 volts (adding the 400 volts DC voltage supplied by E to the 400 RMS voltage of the AC source S) a negatively charged ion flow is produced from pins 20. Conversely as the modulators 12 are made more negative the ion flow diminishes.

Speakers constructed in accordance with the invention can achieve efiiciencies considerably above that achieved in currently used speakers, of the order of sixty percent or more. In addition, a relatively low amount of power is required to modulate the ion flow. A speaker so constructed does not require restricted areas, horns or the like.

The speaker may be made to conform of almost any desired shape, so long as the emitters 8 and collectors 10 are arranged in planes parallel to one another. Thus the speaker may be planar, as shown in FIG. 1, or formed with concave or convex surfaces. Further, the modulators can be attached to the push-pull output of a signal source. So connected the loud speaker could take advantage of the more efficient output of such sources.

The aforedisclosed concept may be embodied in a circuit in which the collector may be either negative or positive with respect to the emitter.

From the foregoing description, it will be apparent that there has been provided an improved electrical transducer capable of efficiently producing audio frequencies. While only a limited number of embodiments and applications of the transducer of the present invention have been described, variations coming within the spirit of this invention will, readily suggest themselves to those skilled in the art. Hence, the foregoing description of the invention shall be considered as illustrative and not inca limiting sense, and that all embodiments of the inventive. concept be protected within the scope of the appended claims.

What is claimed is: 1

1 An electro-acoustic transducer of the type employing the flow of ions, comprising:

a plurality of first electrodes;

at least one second electrode in fixed spaced relationship with said first electrodes, said first electrodes spaced on opposite sides of said second electrodes;

means for providing an electrical potential between said first and second electrodes causing said ions to flow therebetween; and I modulating means coupled to a signal source in pushpull relationship about said first electrodes, in fixed and spaced relationship thereto for'applying a voltage with respect to said first electrodes for controllably restricting the flow of said ions from said first to said second electrodes.

2. A transducer as in claim 1 in which said modulating means comprise:

a third electrode placed proximately to said first electrodes; and

means for providing a varying voltage between said third electrode and said first electrodes for controlling the fiow of said ions bet-ween said first and ,second electrodes.

3. An electro-acoustic transducer as in claim 1 in which there is a sharp projection on each first electrode, and said first electrodes are arranged with their ends in a common plane;

a plurality of second electrodes spaced apart from said first electrodes in a plane and parallel,.to the plane at the ends of said first electrodes and said modulating means comprise a third electrode placed about said projections on said first electrodes;

means insulating said projections from said third electrode; and

means for applying an AC voltage between said third electrode and said first electrodes influencing the flow of ions as said third electrode are made more or less positive with respect to said second electrodes, thereby modulating said ion flow.

4. An electro-acoustic transducer as in claim 1 in which said means for providing an electric potential betweeen said first and second electrodes is a DC source.

5. An electro-acoustic transducer as in claim 3 in which the planes of said first and second electrodes are curved.

6. A transducer for converting electrical energy to sound energy wherein the flow of ions is sought to be controlled, in combination:

an emitter comprising:

a plurality of electrically conductive rigid members arranged in a plane, each of said strips being parallel to one another;

a plurality of electrically conductive pins affixed to said metallic strips and projecting perpendicularly from said plane formed by said strips;

means electrically connecting said strips and said pins thereby forming said emitter;

at least one modulator comprising:

a plurality of hollow cylindrically shaped insulators placed about and afiixed to said pins, said pins projecting through and without said insulators;

a plurality of electrically conductive hollow cylinders placed about and aflixed to said insulators, said conductive cyclinders being spaced from said rigid strips and said ends of said pins;

means for electrically connecting said conductive cylinders, thereby forming said modulators;

collectors comprising:

a plurality of rigid conductive strip like members, said strips being parallel to said strips of said emitters and parallel to one another;

means for electrically connecting said conductive strips forming said collectors;

a first source of DC voltage having positive and negative terminals, said positive terminal connected to said collector and said negative terminal connected to said emitter;

a source of AC voltage have two terminals, a first terminal connected to said modulators; and

a second source of DC voltage having a positive and negative terminal, said positive terminal connected to said second terminal of said source of AC voltage and said second terminal connected to said emitters.

References Cited UNITED STATES PATENTS 1,758,993 5/1930 Wolff 179-113 1,687,011 10/ 1928 Fleischmann 179113 KATHLEEN H. CLAFFY, Primary Examiner A. A. MCGILL, Assistant Examiner 

